Suction box arrangement



A ril 17, 1962 HORNBOSTEL SUCTION BOX ARRANGEMENT Filed Dec. 18

United States Patent 3,029,871 SUCTION BOX ARRANGEMENT Lloyd Hornbostel, Beioit, Wis., assignor to Beloit Iron Works, Beloit, Wis, a corporation of Wisconsin Filed Dec. 18, 1956, Ser. No. 629,138 1 Claim. (Cl. 162-319) This invention relatesto a paper forming machine, and more particularly, to an improved suction boxarrangement for paper machines having a forming wire trained about an open roll.

In one type of paper machine wherein the instant invention is particularly useful, the forming region of the machine comprises a looped forming wire with an open roll or a rotatably mounted foraminous cylinder within the loop of the forming wire for effecting fibrous web formation on the wire. In such an arrangement the roll or cylinder is provided with a foraminous surface comparable to the foraminous surface of the forming wire so that water may pass freely therethrough. An inlet feeds stock onto the wire usually along the region of the upper quadrant of the uprunning side of the cylinder.

This arrangement is used in cylinder type paper machines wherein a short looped forming wire is trained over the cylinder mold; and this arrangement may also be used in a Fourdrinier type paper machine wherein the Fourdrinier wire is trained around an open breast roll. In either arrangement guide rolls within the loop of the wire are arranged so that the wire covers approximately the upper quadrant of the uprunning or oncoming side of the rotating cylinder. Sealing means are associatedwith the wire just before it comes in contact with the oncoming (or uprunning) side of the cylinder and just after the wire is taken away from the off-running side ofthe cylinder. Suction applying means cooperate with such sealing means to create a suction in the interior of the cylinder mold and a pressure differential across the upper quadrant on the uprunning side, soas to assist in drawing water from the stock through the forming wire and the open face of the cylinder.

At higher operating speeds, however, it has been found that the paper machines of the type just described seem unable to effect satisfactory dewatering of the web. The instant invention is based in part on the discovery of the cause of such inadequate dewatering at high speeds and in part upon the discovery of a method and means for preventing the same. It has been discovered that the rotating foraminous cylinders at high speeds rotate so rapidly in the operation of the paper machine that centrifugal forces hold the Water against the interior of the cylinder along the uprunning and top sides of the cyiinder in spite of suction forces applied across the wire.

In fact, a layer of water is actually retained against the inside of the cylinder and the back side of the wire along the upper quadrant of the cylinder on the uprunning side thereof. Such layer of water tends to be thrown back against the wire (and even back into the Web on the opposite side thereof) as the wire is taken away from the offrunning side of the cylinder, and as it passes over the sealing means heretofore employed cooperating with the bottom of the wire in this portion of the wire run.

In the instant invention the sealing means ordinarily associated with the bottom side of the wire at the off running side of the cylinder in the manner hereinbefore employed are not used; but a separate suction box is employed. This separate suction box forms an efiec'tive seal with the wire so that suction within the cylinder is not lost and it also provides a high suction area for additional'dewatering after the wire has left the off-runhing side of the cylinder. In addition, the wire is allowed to dip downwardly as it passes from the off-running side of the cylinder (so as to follow the path of a catenary) for a short distance before the wire curves back up over the suction box. In this arrangement the. suction box presents a convexly curved surface tangentially en- 7 gaging the oncoming side of the wire, so as to permit the V path the water tending to follow along the bottom thereof is thrown oif (also by centrifugal force) and whatever water is still retained is removed as it comes into contact wire to follow the catenary path and come into engage meut with the suction box without excessive wear on the bottom of the wire. As the wire follows the catenary with the surface of the suction box.

It is, therefore, an important object of the instant invention to provide an improved paper machine particularly suited for high speed operation.

It is another object of the instant invention to provide an improved paper machine comprising a looped forming wire, a rotatably mounted foraminous cylinder within the loop of said forming wire for effecting fibrous Web formation on the wire, an inlet feeding stock onto the wire covered cylinder, guide means within the loop of said wire guiding a first reach of the wire away from the cylinder at the off-running side thereof and a second" reach of the wire to the cylinder at the oncoming sidethereof, sealing means in close running relation tosaid second wire reach, a suction box within the loop of said 7 wire engaging said first reach of the wire, said suction box having a convexly curved surface initially engaging the oncoming wire,-and a suction housing connecting said sealing means and said suction box and cooperating with said cylinder to create a'vacuum therein.

Other and further objects, features and advantages of parts shown in section and parts shown diagrammatically.

As shown on the drawings:

In FIGURE 1, a paper machine embodying the instant. invention is indicated generally by the reference numeral- 10 and this machine 10 comprises a looped forming wire.

11, a rotatably mounted foraminous cylinder or openfaced roll 12 for effecting fibrous web formation on the Wire 11 in the region 12a of approximately the upper:

quadrant of the uprunning side (indicated by an arrow) of the cylinder 12, and a guide roll 13 within the loop'of the wire 11 guiding 'a reach 11a thereof away from the cylinder 12 at the off-running side of the cylinder 12,

and an inlet 14 feeding stock onto the oncoming side of the wire covered open cylinder 12.

As will be seen, the wire 11 passes (in the direction Patented Apr. 17,1962

indicated by the arrowheads) along the generally horizontal reach 11a (which will be described in further detail) over the guide roll 13 (a portion of the wire 11 not shown in this view extends beyond the roll 13) and back beneath a lower guide roll 15 and beneath a forward guide roll 16 which guides the Wire along an upwardly directed reach 11!) past vacuum sealing means indicated diagrammatically at 17 onto the upper quadrant 12a of the uprunning side of the cylinder 12. Stock flows through the inlet 14- onto the wire 11 in the region of the upper quadrant 1211. In the region of the quadrant 12a, the wire 11 and the cylinder 12 both provide foraminous cylinder forming surfaces, which are superimposed. Both the foraminous wire surface and the foraminous surface of the open cylinder 12 permit water to pass freely therethrough, so that a fibrous web W may form in the region of the upper quadrant 120.

As will be noted, the cylinder 12 is rotatably mounted on means (not shown) within a suction or vacuum housing indicated generally by the reference numeral 19 which comprises a floor 19a, a forward wall 1% extending upwardly from the floor to the wire seal 17, and a rear wall 190 which, in the prior art, extended upwardly to make wire seal contact with the bottom of the off-running reach 11a (plus, of course, side walls for the housing 19 which are not shown in this view). Also, suitable means for evacuating the housing 19, such as the pump 20, shown diagrammatically, acting through a valve 21 are provided so that a pressure differential may be maintained across the wire 11 and the cylinder surface in the region of the quadrant 12a by virtue of the creation of a vacuum within the cylinder 12 to assist in drawing water from the stock and into the interior of the cylinder 12.

It has been discovered, however, that at high operating speeds a film or layer L of water actually was held against the inside of the cylinder 12 (on the back side of the wire 11) in the region of the quadrant 12a, because the centrifugal force was sufiicient to overcome partially or completely the pressure differential created by the vacuum housing 19. In the prior art, this resulted in throwing water back up against the bottom of the wire reach 11a and/or retaining a layer of water along the bottom of the wire reach 11a as it separates from the off-running side of the cylinder 12. Also, in this arrangement, if a felt covered suction pickup roll were used in a cylinder mold type machine for attempting to pick up the web, this suction roll would tend to draw water up from the cylinder 12 so that the web would be too wet.

In the instant invention, a suction box 18 is mounted at the top of the rear housing wall 190 and makes sealing engagement with the bottom of the wire reach 11a. The suction box 18 is also connected to vacuum creating means such as the pump through a valve 22 and the suction box 18 operates at a much higher vacuum than that which can ordinarly be obtained within the housing 19. The suction box 18 thus functions separately and apart from the suction housing 19 (although a portion of its structure serves to complete the structure of the suction housing 19 and to provide a seal therefor).

As will be seen the top 18:: of the suction box 18 is provided with the customary perforate surface which engages the bottom of the wire reach 11:: for the purpose of applying vacuum thereto and dewatering the web W carried on the top side of the reach 11a. In ordinary operation, a wire is drawn across the top of one or more suction boxes under a reasonable amount of tension so as to minimize wear on the wire particularly at the oncoming edge of the suction box. As here shown, however, the top 18a of the suction box is curved downwardly in the direction from which the wire 11 approaches so as to conform in part to the upcoming side of the catenary path to receive the wire with a minimum of Wear and to permit the wire 11 to dip downwardly in its catenary path as it separates initially from the cylinder 12. As will further be appreciated the catenary path of the wire 11 effectively permits the wire 11 to throw off substantially all of the water tending to be retained on the bottom thereof (particularly as the wire 11 reverses in direction from downward travel to upward travel at the bottom of the catenary path).

Referring now to FIGURE 2, it will be seen that elements therein functioning in the same manner as elements shown in FIGURE 1 are given the same reference numeral in the series. In FIGURE 2 there is shown a cylinder type paper machine indicated generally by the reference numeral 100 comprising a looped forming wire 111, a rotatably mounted foraminous cylinder or open cylinder mold 112 for effecting fibrous web W formation on the wire 111 in the region 112a of approximately the upper quadrant of the uprunning side (indicated by an arrow) of the cylinder 112, and a guide roll 113 within the loop of the wire 111 guiding a reach 111a thereof away from the cylinder 112 at the off running side of the cylinder 112, and inlet 114 feeding stock onto the oncoming side of the wire covered open cylinder 112. The wire return arrangement (not shown) and the vacuum housing and sealing arrangement 117 described in connection with FIGURE 1 are the same for the device of FIGURE 2. It will also be seen that the suction box 118 mounted on the rear wall 119c of the main suction housing 119 is the same as in the arrangement shown in FIGURE 1, with a downwardly curving top 118a initially engaging the wire reach 1 1a at the upcoming side of its catenary path. As will be seen, the suction box 118 is positioned between the cylinder 112 and the guide means 113. A suction pickup roll 123 with the suction area 123a is wrapped by a felt F and urges the felt downwardly against the top side of the wire run 111a in order to pick up the web W therefrom. The felt covered suction roll 123 engages the wire reach 111a after the suction box 118, and as here shown, between the suction box 118 and the guide means 113. In this arrangement, maximum dewatering of the web W is obtained before pickup on the felt F, not only through the movement of the Wire 111a through the catenary path to eliminate water adhering to the bottom of the wire, but also because of the high suction applied to the Wire 111a with the web W thereon as it passes over the suction box 118.

It will be understood that modifications and variations may be elfected without departing from the spirit and scope of the novel concepts of the present invention.

I claim as my invention:

In a paper making machine, a rotating foraminous cylindrical forming roll, a travelling forming wire trained over the surface of said forming roll and being of sutficient length to extend in a generally horizontal reach from the top of the off-running side of said forming roll, guide rolls aiding and supporting the travelling forming wire, an inlet feeding stock to the up-running side of said forming roll and wire thereon for depositing a layer of paper fibers, a housing enclosing the lower portion of the forming roll defining a vacuum chamber therein for drawing water through an exposed tip-running area of the roll, said housing having a rear wall extending upwardly spaced from the down-running side of the roll, a suction box mounted at the top of the rear housing wall and having a perforate upper surface making sealing engagement with the bottom of the wire reach. the top of the suction box curved downwardly in the direction from which the wire approaches from the roll, an unsupported portion of wire reach between the roll and the suction top draping downwardly in a catenary path with said top of the suction box conforming in the leading part to the curvature of the catenary to permit the wire to dip downwardly, first means for creating a vacuum in said housing so that said catenary portion of the reach is subjected to a pressure differential, and

References Cited in the file of this patent UNITED STATES PATENTS 5 Buchanan June 30, 1914 Reynolds Aug. 7, 1917 Wagner Apr. 21, 1925 Sweeney July 14, 1931 10 Brawn June 28, 1932 Poeschl et a1 Dec. 12, 1933 6 Sherman Mar. 26, 1935 Engert Mar. 31, 1936 Metcalf June 13, 1939 Planer Sept. 13, 1955 Goodwillie Nov. 4, 1958 Berlyn Apr. 21, 1959 Hornbostel Nov. 1, 1960 FOREIGN PATENTS Germany June 12, 1930 

